Pinterest and Facebook have the most mild distribution, which makes sense: Facebook is pervasive enough to closely represent the U.S. Browsing Population, and Pinterest doesn’t have any sort of age-focused component to it. It’s all self-curated content.Tumblr has an understandable polarity towards a younger demographic, a trend opposed by LinkedIn’s emphasis on a higher age group, and both Twitter and Google+ show a propensity for the middle-aged range.